Chronic and severely stressful situations, like those connected
to depression and posttraumatic stress disorder, have been associated
with smaller volumes in "stress sensitive" brain regions,
such as the cingulate region of the cerebral cortex and the hippocampus,
a brain region involved in memory formation. A new study, published
by Elsevier in Biological Psychiatry, suggests that chronic insomnia
may be another condition associated with reduced cortical volume.

Using a specialized technique called voxel-based morphometry,
Ellemarije Altena and Ysbrand van der Werf from the research group
of Eus van Someren evaluated the brain volumes of persons with
chronic insomnia who were otherwise psychiatrically healthy, and
compared them to healthy persons without sleep problems. They
found that insomnia patients had a smaller volume of gray matter
in the left orbitofrontal cortex, which was strongly correlated
with their subjective severity of insomnia.

"We show, for the first time, that insomnia patients have
lower grey matter density in brain regions involved in the evaluation
of the pleasantness of stimuli, as well as in regions related
to the brain's 'resting state'. The more severe the sleeping problems
of insomniacs, the less grey matter density they have in the region
involved in pleasantness evaluation, which may also be important
for the recognition of optimal comfort to fall asleep," explained
Altena. She added, "Our group previously showed that insomniacs
have difficulties with recognizing optimal comfort. These findings
urge further investigation into the definition of subtypes of
insomnia and their causal factors, for which we have now initiated
the Netherlands Sleep Registry."

Dr. John Krystal, Editor of Biological Psychiatry, commented,
that "insomnia is a common feature of nearly every psychiatric
condition associated with reduced cortical volume; in fact, it
is a common symptom of psychiatric disorders or high levels of
life stress, generally. The study by Altena and colleagues suggests
that there are additional risks of not treating insomnia, such
as detrimental effects on the microstructure of the brain."